Re: Digital negative novice needs help.

From: Gregory Popovitch <greg@gpy.com>
Subject: RE: Digital negative novice needs help.
Date: Fri, 21 Apr 2006 21:21:15 -0400

> Also, there are some facts. Ektaflex prints known to resolve 20 lp/mm
> are visibly less sharp to the eye that other types of RA4 paper prints
> resolving 65 lp/mm. How do you explain this if 10 lp/mm is the resolution
> limit of the eye?

Again, resolution limit and accutance are very different matters. You
should be discussing these matters in terms of MTF (modulation
transfer function) instead of resolvability and accutance, both of
which are rather subjective matters. (resolvability is often given in
numbers but there is no single established scientific method to
measure those numbers without human judgement, not that it matters a
lot in most practical cases.)

There are two important papers on this topic published in volume 15,
issue 2 of Photographic Science and Engineering (1971). One is by
Nelson and the other Higgins.

> I think that your statement "increased resolution does
> not necessarily mean the edge contrast is greater", while correct,
> is misleading. I doubt that in practice you will be able to produce
> high acutance, low resolution prints. If the resolution is low, then the
> edge sharpness will not be satisfactory to the eye, and I think that's
> what Ctein was saying.

It's easy to make high accutance, low resolution image. Using
old technology film developed in accutance developers, and then
magnify by a large factor.

On the other hand, if you develop T-MAX 100 in D-76 and print it at
moderate magnification, you get low accutance, high resolution image.

With digital signal processing based image processing on computers,
any of these things is possible.
Received on Fri Apr 21 23:57:22 2006